I got a signup from a new spam domain which is txt.bellmobility.ca, with the name “IzLCwSMqVL”. I would advise blocking it. Your spam blocklist should look like this:
vtext.com
txt.att.net
tmomail.net
mymetropcs.com
msg.telus.com
pcs.rogers.com
fido.ca
txt.bell.ca
email.uscc.net
txt.bellmobility.ca